Closed Loop Voltage Control (CLVC) is a power management technique that reduces the average dynamic power consumption of an integrated circuit (IC) by dynamically adjusting the supply voltage of a target circuit of the IC to a minimum level required for proper operation.
Typical CLVC systems make an indirect measurement of the target circuit's present performance and adjust the supply voltage, based on the measurement, to maintain a target performance level. The indirect measurement of the target circuit's present performance is provided by an emulation circuit, normally a programmable delay line, that is co-located on the IC with the target circuit. Instead of measuring delay times along a critical path of the target circuit, a measurement is made of the delay propererties of the emulation circuit. The delay line is powered by the same controlled voltage level that also powers the target IC, and the measured delay times are based on the delay properties of the delay line.
Based on a comparison between the measured delay times and a target delay time, an adjustment of the supply voltage is made. To minimize power consumption, the supply voltage is kept as low as possible while still meeting a given performance level.